Solid non-hygroscopic iron salt and the preparation thereof



'fied before it can beused.

UNITED STATES PATENT oFFlcE.

OTTO 3615M, OF DABMSTADT, GERMANY.

No Drawing.

To all whom it may concern: 7

Be it knownthat I, Or'ro RoHM, a citizen v of the Free State ofWurttemberg, in the Iron Salts and the Preparation Thereof, for

which I have filed applications in Germany, December 27 1918,,and April11, 1919, and I do hereby declare the following to be a full, clear, andexact description of the same.

For various technical purposes, as for instance for tanning, chlorid ofiron can be well made use of. This product has however two objectionableproperties, which make its employment on a large scale 'difli- .cult.

A water solution of chlorid of iron can betransported only in glassvessels, because it is very liable to sethydrochloric acid free andtherefore destroys all other vessels. The transport on a large scale inglass ves-' sels is not practicable, as in addition, the disadvantageoccurs, that the salt becomes crystallized in winter and has to belique- If it is desired to send the chlorid of iron in crystallizedstate, then the watersolution can be boiled only in vessels of clay,glass, quartz or precious metal and the vapors of the hydrochloric acidevaporating with the steam of the water must be a ain condensed.

These technical difiiculties induced the inventor to search for asubstitute for the chlorid of iron, which does not possess thedisadvantageous properties of same and he was successful in producing-asolid iron salt nonhygroscopic and especially advantageously suitablefor\ tanning purposes.

According to the invention chlorin takes effect on sulfate of iron ina-state of solutionfcontaining crystalwater or water free. By this a newiron salt is created, the composition of which corresponds to theformula FeSO,Cl or FeS O CL6H O. If chlorin is passed over crystals ofsulfate of iron, which as is well known,'co ntain 7 molecules of water,then they melt and there results direct a 60% solution of. FeSO Cl 'inthe Water; If the solution isconcentrated b the water bath, then a syrupis obtaine Specification of Letters Patent.

Application filed July 16,

Patented June 28, 1921,. 1920. Serial no. 396,876.

which is transformed into a yellow crystal cake, when it cools and isallowed to stand a little time.

Itwas further observed that when boiling down takes place under ordinaryatmos pheric pressure, disturbances can occur b hydrolysis of theferri-sulfatechlori which can be avoided however by effecting theboiling down of the solution under lower temperature, that is underlower air pressure. If the solution is boiled down till it containsabout 37% water (corresponding to 6 mol. H 0 to FeSO,,Cl) then thecooled and if necessary inoculated mass becomes solid and forms solidcrystals in a short time of the composition FeSOfiLGH O.

That a chemical combination and not a mixture has taken place, is provedby the fact that the new salt dissolves inalcohol, Whereas ferricsulfateis insoluble. The produced salt is also stable indamp air, whereas amixture of ferric-chlorid and ferric-sulfate becomes liquefied.

In the manufacture of the new iron salt. the otherwlse necessarymeasures, when,

boiling down salt fluids, are dispensed with. As the stable product isnot hygroscopic, it is most favorable as regards packing and transport.Under these circumstances .it is very possible that the new salt willfind a market not only for tanning but also for other purposes.

Examples.

1. Over 600 kilosiron scrap of 9095 percentage of iron 6300 litersofwater are poured and 1050 kilos of sulfuric acid of 96% are added.After the fluid has become tered and treated with chlorin, tilltheferrous-sulfate has disappeared. The solution thus treated-with chlorinis boiled down at 150 mm; pressure and 50. to the specific gravity of1.775 or 65 Bl at 40 degrees; there is then about 37% of water containedin same. The hot mass is poured into molds, cooled and inoculated. Itbecomes solid in a few hours and forms a hard yellow crystal cake offerri-sulfate-chlorid of the formula FeSQflLGH O.

The product melts at 50-55;degrees,.dissolves very easily in water,slightly less so neutral, the solution of ferrous-sulfate is filinalcohol. In most organic solvents it is Calculated for Found.F6SO4C'L6H2O. Fe :18 .91-% Fe :18 .92% S0 :31'.69%.. S0 :32 43% Cl :11.86% Cl :11 .95.% 11,0:37 .54% H;o 3e .7

The same salt crystallizes also out of solutions' prepared in adifferent manner, if they contain, iron, chlorin and sulfuric acid. inthe weight proportions corresponding to the combination FeSO CL6H O "andhave been boiled down to a water percentage of 37% in a space withreduced air pressure.

Finally the boiling down can be quite avoided if all the ingredients ofthe ferricsulfate-chlorid including the water are brought together inthe same proportion, in which they are contained in the new product. Onewould therefore bring to ether either: 1 mol. of ferric-chlorid (F eClwith 1 mol. ferric-sulfate and 18 mol. of water or 1 mol. offerric-chlorid (Fecl with 1 mol. of sulfuric acid (H SO and 6 mol. ofwater. In the latter case the hydrochloric acid, which is delivered mustbe removed.

The formation of the ferri-sulfate-chlorid FeSO CL6H O takes placeaccording to the equations Feo1,+Fe, (s0 18H,0=

FeCl +H SO +6H O= FeSO Cl.-6H O+2HCL 2. 270 parts of iron-chlorid (FeClfiH o) are powdered and placed in 98 parts of 100% sulfuric acid. At thefinish of the development of the hydrochloric acid, which can beaccelerated by reduced air pressure, the reaction product solidifies asthe same firm yellow mass-as above.

3. 270.5 parts of-crystallized iron chlorid- (FeCl .6H U) are intimatelymixed with 562 parts of crystallized ferric-sulfate (Fe (SO 9H,O) andthe mixture exposedto' humid air, whereby it partly dissolves.

After some time the product solidifies as a yellow crystallized hardmass consisting of ferri-sulfate-chlorid.

'In the different processes of making my ferrirsulfate-chlorid no acidis added to the re-action. mixture, and any acidity is due to hydrolysisof salts present.

I claim: i 1. A process for producing a non-hygroscopic iron salt,especially suitable for tanu 0 4+ nlng purposes, comprising intermixingFe ions, SO 'ions and chlorin, in a medium which has no greater aciditythan that pro-- effect on green vitriol under conditions of no greater.acidity than that produced by the said ingredients.

3. Process for the production of nonhygroscopic-iron salt, especiallysuitable for tanning purposes, comprising concentrating the watersolutions, which contain iron, chlorin and sulfuric acid in theproportions by Wei ht corresponding to the formula Fe O Cl, underreduced air pressure until a water content of 37% is reached.

' 4. Process for the production of a nonhygroscopic iron salt,especially suitable for. tanning purposes, comprising bringing togetherall the radicals of crystallized ferrisulfate-chlorid including thewater in the weight proportions of the formula FeSOfiL 5 fin iron saltcontaining ferric iron, two valency bonds of which are attached to anSO, radical and oneboncl to a Cl radical.

6. A chemical compound having the formula FeSOQCl.

'7. A chemical compound having the formula FeSOfil and including waterof crystallization. v

8. A chemical compoundhaving the formula FeSO GL6I-I O.

In testimony whereof, I have signed my name to this specification inthe'presence of two subscribing witnesses.

' DR. orTo noHM.

Witnesses:

Hneo T. Anon, Dr. WILHELM ANDRES.

